Use of plastic in the manufacturing industry exclusively depends on skillfulness over forming the substance into desirable shapes. ‘Thermo-forming’ of plastics emerges out of the process of subjecting the plastics or thermoplastics to heat to make pliable for easy transformation to specific forms. Since vacuum is an important part of the process, it is also called vacuum forming. Basically, forming composes of two processes – preheating to a determined temperature and vacuuming. Vacuum draws or sucks plastic sheet to take the precise form of mold while preheating makes the plastic bendable in the automated machines. Further step involves trimming the shaped forms with CNC device; any further detailing is done with help of applying pressure.
The molds play very important role in vac forming. While the ‘male’ molds give specific form to the plastic, the ‘female’ molds are used for desired finishing and texture of created shapes. The process is oldest shaping technique and still used popularly. All variants of plastics you find around in everyday life are shaped by this process.
Simple steps of executing the process in industrial situations, is pouring heated plastic over the molds in a vacuum chamber. This ensures very intimate adherence of plastic to the molds. Of course, in manufacturing situations, the demand of extremely sensitive detailing of the shapes is fulfilled by treatment under further hydraulic and pneumatic processes.
The use of vac forming technique is generally applied for creating shallow depth shapes; a very common example is blister packs used by pharmaceutical product packaging. The technique is also used for making small flattish or less contoured objects. The high polystyrene impact variants are conventional thermoplastics and easy to heat treatment by placing around aluminum or wooded molds. There are specific techniques in this category of forming, some suitable for flatter shapes while others for making mechanical components. The method is also suitable for shaping transparent acrylic that has wide usage in air crafts.
Some of the typical present day usage of vac forming technique are specifically shaped enclosures used in medical therapy units, ATM enclosures, kiosks, dashboards, covers for engines and other machinery, enclosures in railway coaches and more. The parameters of high degree of perfection in forming are concern in specific areas of operation. These are designing of part and tooling; and selection of material and the process to use. Basic advantages of process are fast prototyping hence less time taking in comparison to other techniques and low start up cost. The process takes low cost pattern materials like wood, aluminum, high density epoxy and foams. The molds are quite suitable to repeat jobs.
Post time: 03-23-2017